Pipes with bent portion for transporting powder or grains by air power



Oct. 15, 1968 SHOZO OKA 3,405,738

PIPES WITH BENT PORTION FOR TRANSPORTING POWDER OR GRAINS BY AIR POWER Filed June 14, 1965 INVENTOR.

SHOZO OKA BYE ' attorney a United States Patent 3,405,738 PIPES WITH BENT PORTION FOR TRANSPORTIN G POWDER OR GRAINS BY AIR POWER Shozo Oka, 35 Otakimachi, Nakana-ku, Tokyo, Japan Filed June 14, 1965, Ser. No. 463,590 Claims priority, application Japan, June 19, 1964, 39/ 47 ,7 40 1 Claim. (Cl. 138-39) ABSTRACT OF THE DISCLOSURE As the grain 'feed direction within the pipe changes from the vertical gradually to a descending inclined direction, the cross section of the pipe grows continuously larger throughout the change of direction. The cross section of the pipe in the descending incline grows continuously smaller to a discharge in a receiving vessel.

In the case of transporting a powder or grains through a transport pipe by air power there occurs, in general, a depression in transporting capacity suddently at a bent portion of the pipe. This drawback leads to a bottleneck in the entire transport pipe, then disturbing the transport capacity of the entire transp0rt-pipe.

The present invention relates to improvements in pipes formed 'with a bent portion for transporting uniform grains such as crop grains, grains of coal or rocksalt nonuniform in shape by air power in such a manner that the extent of such bottleneck as aforesaid can be reduced remarkably even in the case of high concentrations of the powder mixture.

SUMMARY OF THE INVENTION One of the characteristics of the present invention is that the cross sectional area of a bent portion of the transport pipe is enlarged gradually from the initial part of bending to the final :part thereof as far as the pipe is bent.

Another characteristic of the present bent pipe is that the radius of curvature of the inner surface of pipe wall at the outer side of bending near the final part of said bending is made larger than that near the initial part thereof.

Another characteristic of the present invention is that a straight transport-pipe is connected to the final part of bending in such a manner that it is tipped downwardly.

Another characteristic of this connecting and straight pipe is that the cross sectional area of each portion of said straight pipe is reduced gradually by order.

The invention will be explained in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front view of the transport pipe of the present invention.

'FIG. 2 is an enlarged front view of one embodiment of the present invention to show a bent portion thereof and the cross sectional area of each portion of the pipe attached thereto.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 reference 1 is a suction opening for a powder or grains, 2 the initial part of a bent portion of the transport pipe, 3 the final part thereof, 4 the final end of a connecting and straight pipe which is tipped for an angle of a downwardly from said final p'art 3 and 5 a collector for the powder or grains. R shows the radius of curvature of the inner surface of the external pipe wall bent near the initial part of bending and R the radius of curvature of the inner surface of the external pipe wall bent near the final part 3 of bending.

3,405,738 Patented Oct. 15, 1968 Concerning the transport pipe for the powder or grains, the cross sectional area s of the initial part of bending is always increased gradually as far as the pipe is kept on bending until it reaches a maximal area S at the final part of bending in a characteristic manner of the present invention. Namely, the bent portion in the pipe is neither reduced gradually in cross sectional area nor does any equal cross sectional area thereof remain throughout, notwithstanding that the transport pipe is bent.

This bent pipe is characterized by the fact that the radius of curvature R of the inner surface of the external wall of the pipe bent near the final part of bending is made smaller than the radius of curvature R of the inner surface of the external wall of the pipe near the initial part 2 of bending.

This bent pipe is characterized further by the fact that a straight transport-pipe is connected to said bent pipe in a manner of the former being tipped for an angle of a downwardly from the final part of bending.

This straight transport-pipe is characterized by the fact that it starts from a cross sectional area equal to S of the final part 3 of bending and decreases gradually until it reaches nearly the cross sectional area s of the initial part of bending.

According to one embodiment of the present invention, the extent of cross sectional 'area of the transport pipe is kept constant and then its height H starting from the initial part 2 of bending, is increased gradually until it reaches its maximal height H at the final part of bending such that the ratio of H to H is arranged 1.2-4.0 thereby representing one of the characteristics of the present invenion.

According to this bent pipe, good results have been obtained by making the radius of curvature R of the inner surface of the external pipe wall near the final part 3 of bending smaller than the radius of curvature R of the inner surface of the external pipe wall near the initial part 2 of bending, namely, arranging the ratio of R to R to be 1.2-3.0.

Moreover, good results have also been obtained by arranging the downward tip-over angle of the straight transport-pipe connected to the final part 3 of bending to be 10-30 and making the cross sectional area of the final part 4 of said straight transport-pipe almost equal to the cross sectional area s of the initial part 2 of bendmg.

The action of the transport pipe for a powder or grains by air power will be explained in further detail.

The possibility of a powder or grains being transported with little resistance by air power in a transport pipe is ascribed to the fact that the powder or grains can be supplied under floating conditions in an air flow.

However, when a bent portion is present in the transport pipe, the powder or grains for transport are destined to impinge on the inner wall of the external side of bending at said bent portion of the transport pipe until the moment of inertia of said powder or grains is caused to change.

Consequently, the powder or grains are liable to lose their floating condition and reduce their proceeding speed due to their friction with the inner surface of the external pipe wall and the impinging action and friction among the grains themselves until they assemble together in the wall of the pipe and travel at a slow speed. When such slow flow approaches the final part 3 of bending, it assumes a condition approximate to blocking the pipe, The assembled layer of grains having reduced their flowing speed will occupy the greater part of the cross sectional area S of bent pipe thus leaving only a small passage of air flow therein.

The cross sectional 'area of this small passage of air flow becomes extremely narrow at this stage. Therefore, the speed of air flow passing through this area is increased more and more until the air cannot flow any more at its limit speed, namely, under the aspirating force of the apparatus.

The passage of air flow is reduced in size to such an extent that the air fiow cannot continue any longer under said conditions and the amount of air being sucked into the suction opening of the transport pipe cannot be increased any more.

As a result, the powder or grains cannot be sucked up any more.

In this manner, the capacity of transportation of the powder or grains will be depressed considerably.

In view of this trouble, one of the characteristics of the present invention will be realize-d such that the cross sectional area s of the initial part 2 of bending is gradually increased up to S of the final part of bending to reduce the speed of said assembly layer of powder or grains in said bent portion, and increase the cross sectional area s' of the assembly layer of the powder or grains, the speed of which has been thus reduced. With the increase of the cross sectional area of the assembly layer of powder or grains, the air flow is shielded from further reduction of its passage area. These factors work cooperatively to bring about a remarkable increase in transporting capacity of the powder or grains.

Moreover, by arranging the radius of curvature R near the final part 3 of bending to be smaller than the radius of curvature R near the initial part of bending as one of the characteristics of the present bent pipe, it is made possible to cross the flow of the assembly layer of the powder or grains travelling at a slow speed and air flow at a considerably great speed so that both slowed-down and fast powders and grains can be returned to their floating condition in the air, thereby increasing the speed of transport again.

Moreover, by providing a downward tip-over angle of a for the straight transport-pipe connected to the final part 3 of bending also as one of the afore-said characteristics of the present invention, it is made possible to drop the powders or grains by gravitation for dispersing and floating said powders or grains in high-speed air of transport, thereby increasing the transport capacity of the powder or grains.

Further, the cross sectional area S of the connected portion of said straight transport-pipe at the final part 3 of bending is gradually reduced towards the top end thereof, such arrangement being found effective in floating the powder or grains in transporting air and consequently increasing the capacity of their transport.

As explained above, all the characteristics of the presout invention come to work not only individually in an effective manner, but also one cooperates with another so that the transporting capacity of the transport pipe can be improved remarkably.

What is claimed is:

1. In combination with an elongated apparatus, such as a hopper, for handling granular materials, having a source of vacuum and a suction inlet orifice connecting with a material transport pipe of said material, while deposited below suction orifice, a transport pipe for conveying said material upwards into said suction inlet orifice of said apparatus, comprising:

a first vertical linear transport pipe sector (1), having a bottom end provide-d with a suction inlet to be inserted into a pile of said material, said first sector having a variable cross sectional area increasing continuously symmetrically upwards and a length exceeding the height of said suction orifice from the level of said suction inlet of said first sector;

a second, bent-shaped transport pipe sector (2), in-

tegrally joined with its inlet end to the upper outlet end of said first sector, both ends having at the joint the same cross section;

the cross sectional area of said second sector continuously increasing into a symmetrically swelling towards the outlet end of said second sector; and a third linear pipe section (3), integrally joined with its inlet end to the outlet end of said second sector, both ends at their joint having the same cross section, the cross sectional area of said third sector decreasing continuously and symmetrically towards said suction inlet orifice of said apparatus;

the radius of curvature of the bend of said second sector symmetrically continuously increasing from its inlet end (R to the outlet end .(R thereof to a point at which the said third sector is directed downwardly linearly into said suction orifice of said apparatus at a sharp angle to the said first sector.

References Cited UNITED STATES PATENTS 213,709 3/1879 Taggart 30259 1,837,901 12/1931 Fottinger et al. 138-39 1,890,562 12/1932 Clute 30259 2,076,873 4/1937 Arnold 30264 LAVERNE D. GEIGER, Primary Examiner.

B. KILE, Assistant Examiner. 

